JP2002345161A - A plurality of voltage output type power supplies for vehicle and controlling method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plurality of voltage output type power supplies for a vehicle, capable of decreasing voltage (or capacity) dispersion between battery blocks. SOLUTION: A set of batteries 13 is made up of a lower electricity storage block 111 that outputs a lower power source voltage to a lower voltage load 161 and higher electricity storage blocks 112, 113 that are connected in series to the higher potential side of the lower electricity storage block 111 and output a higher power source voltage to a higher voltage load 162 with the lower electricity storage block 111. DC-DC converters 181, 182 convert the voltage across the terminals of the higher electricity storage blocks 112, 113. By impressing the converted voltage across the lower electricity storage block 111, only the lower electricity storage block 111 is charged by the stored electric power of the higher electricity storage blocks 112, 113.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiple voltage output type power supply and a control method thereof.

[0002]

2. Description of the Related Art In a recent vehicle power supply, in addition to a normal power supply voltage (about 12 V) output to a conventional vehicle electric load, a higher power supply voltage (for example, 36 V) is applied to a large electric load.
V) or a low voltage (for example, 5
V), a multiple power supply voltage output type vehicle power supply system has been proposed. According to the multiple power supply voltage output type vehicle power supply system, power transmission loss to a large on-vehicle load can be reduced, the wire harness can be reduced in size and weight, and the power supply device for the control device can be simplified. In this case, since it is uneconomical and disadvantageous in terms of weight and loading space to provide a different battery pack for each power supply voltage, an additional battery block is superimposed on the battery block for low power supply voltage output to provide high voltage output. Has been proposed.

However, in this multi-voltage output type battery pack,
The discharge amount differs between the low power supply voltage output battery block and the additional battery block. Therefore, in order to additionally charge the battery block for low power supply voltage output, it has been conventionally proposed to add a DC-DC converter for converting the electric power of the assembled battery and supplying power to the battery block for low power supply voltage output. ing.

Further, the SOC of each cell constituting the assembled battery is
Since the control of the individual cells complicates the circuit, the SOC control is generally performed collectively assuming a plurality of cells as one cell. However, in this case, since the SOC control is not performed for each unit cell, the variation in charge / discharge characteristics between the unit cells increases with repeated charging / discharging of the assembled battery. As a result, as a whole, the SOC falls within the reference range. May be overcharged or overdischarged, despite being within the range. In particular, a lithium-based battery is vulnerable to such an overcharged state or an overdischarged state. Therefore, among the single cells (cells), the terminal voltage (hereinafter, referred to as the minimum SOC) having the smallest SOC (or the smallest terminal voltage) is obtained.
Until the terminal voltage of the other cells decreases to the terminal voltage of the other cells, a discharge circuit for discharging these other cells is provided.

[0005]

However, in the above-described multiple voltage output type assembled battery, the SOC (terminal voltage) between the unit cell of the battery block for low power supply voltage output and the unit cell of the additional battery block is set. There is a problem that the variation of the control circuit easily occurs and a problem that the control circuit configuration is complicated.
For example, a low power supply voltage output battery block may monitor a current supplied to a low-voltage load and control the DC-DC converter to output a current equal to this current. Accumulates, a large SOC (terminal voltage) error occurs between the battery block for low power supply voltage output and the additional battery block, and the problem of overcharge and overdischarge occurs.

In order to solve this problem, it is possible to make the SOC (terminal voltage) of each cell constituting the assembled battery equal to that of the smallest cell by using the above-mentioned discharging circuit. In addition, since the SOC (terminal voltage) tends to be different between the battery blocks, there is a problem that the power loss and the heat generation due to the operation of the discharge circuit increase.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a vehicle multiple voltage output type that can eliminate variation in SOC (terminal voltage) between cells in a battery pack while reducing wasteful power loss. It is intended to provide a power supply.

[0008]

According to a first aspect of the present invention, there is provided a power supply device for a multiple voltage output type vehicle, wherein a lower power storage block for outputting a low power supply voltage to a low voltage load, and a lower power storage block. A plurality of HIGHERs connected in series and connected in series to each other to output a high power supply voltage to a high voltage load together with the lower power storage block.
R) a power storage block, and a power supply unit for a multiple voltage output type mounted on the vehicle including a power generation unit that transmits power to a series-connected power storage block group including the lower power storage block and the higher power storage block connected in series with each other; A DC-DC for supplementary charging of the lower power storage block, in which only the lower power storage block is charged with the stored power of the higher power storage block by converting the voltage between both ends of the higher power storage block and applying the voltage to both ends of the lower power storage block. A DC converter, and an inter-block power transmission control unit that detects and compares electrical parameters related to the average cell voltage of each of the battery blocks, and that substantially matches the average cell voltage of each of the battery blocks based on the comparison result. It is characterized by:

According to this configuration, the higher power storage block and the lower power storage block are connected in series to supply power to the high voltage load from the higher end of the higher power storage block, and to supply power to the low voltage load from the connection point of both battery blocks. It is composed of a voltage output type power storage unit and a DC-DC converter for transmitting power from the higher power storage block to the lower power storage block. In other words, in order to supply power to both the high-voltage load and the low-voltage load, the lower power storage block is more easily discharged (voltage or SOC is reduced) than the higher power storage block that supplies power only to the high-voltage load. Then, the inter-block power transmission circuit performs power transmission from the higher power storage block to the lower power storage block. This allows the inter-block power transmission circuit to be a relatively simple one-way power transmission type D
The device can be constituted by a C-DC converter, and the weight, size and cost of the device can be reduced by simplification of the circuit as compared with the related art.

Further, in this configuration, the inter-block power transmission control section detects electric parameters related to the average cell voltage for each of the battery blocks, compares them, and based on the comparison result, compares the electric parameters of each of the battery blocks. The average cell voltage is made substantially equal. As a result, the average cell voltage of each battery block is equalized, so that the capacity variation between the battery blocks can be eliminated by simple arithmetic control. Also, D
In the control of the C-DC converter, there is no need to provide a current sensor for detecting the low-voltage load current output to the low-voltage load by the low power supply voltage output battery block, and the output value of this current sensor and the output current of the DC-DC converter are eliminated. Therefore, the average capacity state of the cells in each battery block can be made to coincide with each other by a simple control since the error between the battery blocks does not accumulate in the battery block for low power supply voltage output.

If the average cell voltage is used as the electric parameter, the electric parameter can be easily obtained by dividing the battery block voltage by the number of cells in the battery block, and the calculation becomes particularly simple. In addition, the minimum cell voltage of each battery block may be adopted, or the average SOC or the minimum SOC may be adopted.

According to a second aspect of the present invention, there is provided the power supply apparatus for a multiple voltage output type vehicle according to the first aspect, further comprising a plurality of cell voltages individually connected to the respective battery blocks each having a plurality of cells connected in series. An equalizing circuit is provided, wherein each of the cell voltage equalizing circuits equalizes the voltage of each of the cells in the battery block to which the cell is connected.

That is, in this configuration, since the cell voltage equalizing circuit is provided for each battery block, even if the SOC (terminal voltage) is likely to differ for each battery block as in the present invention, the cell voltage equalizing circuit is provided. Compared to the case where each cell of the battery is matched with a single cell voltage equalization circuit,
Power transmission or discharge for cell voltage equalization can be significantly reduced, and power loss and heat generation for cell voltage equalization can be significantly reduced.

Further, the cell voltage equalization circuit for each battery block of this configuration can eliminate the cell voltage variation between the battery blocks, but cannot eliminate the cell voltage variation between the different battery blocks. Since the power transmission control unit performs control to make the average cell voltage of each battery block substantially equal, the joint operation of the inter-block power transmission control unit and the cell voltage equalization circuit for each battery block enables
The capacity state of each unit cell of the assembled battery can be matched well.

More specifically, when performing inter-block power transmission from a higher power storage block to a lower power storage block using a DC-DC converter, a problem that arises is that each battery block really determines the practical minimum capacity of each battery block. Is not the average cell (average cell capacity), but the lowest cell voltage (lowest SO
(With C).

That is, although the inter-block power transmission control for equalizing the average cell voltage is simple, when the inter-cell voltage variation in the battery block is large, the SOC that can be practically discharged between the battery blocks is accordingly adjusted. And the benefits of inter-block transmission decrease.

It is useful to detect and match the minimum cell voltage or the minimum SOC among the cells in each battery block, but this complicates the circuit configuration or operation. In addition, the minimum SOC between the battery blocks is matched,
The variation in SOC or voltage between the cells remains unchanged, and the decrease in the dischargeable capacity is not always recovered.
In some cases, there is a risk that the cell having the maximum cell voltage is overcharged by the inter-block power transmission.

It is also possible to equalize the voltage variation among the cells. Conventionally, techniques for equalizing voltages between cells include:
There are known a minimum cell voltage matching method in which each cell voltage is made equal to the minimum cell voltage by discharging, and an electromagnetic method in which power is transmitted and received electromagnetically between cells. However, in the former method, the cell voltage of the lower power storage block and the cell voltage of the higher power storage block tend to be different because the discharge condition is completely different between the lower power storage block and the higher power storage block in the multiple voltage output type power storage device. There is a problem that the discharge loss increases, and the latter method has a problem that the circuit configuration becomes complicated.

Therefore, in the present embodiment, in order to solve these problems, a cell voltage equalization circuit is provided for each battery block, and each cell voltage equalization circuit is provided within the battery block to which the cell block is connected. Each cell voltage is to be equalized. More specifically, in the case of a two-block configuration including one lower storage block and one higher storage block, each cell voltage of the lower storage block is equalized by a cell voltage equalizing circuit for the lower storage block, and each of the higher storage blocks is equalized. The cell voltage is equalized by a cell voltage equalization circuit for a higher block. Therefore, in this configuration, the cell voltages are equalized between cells having the same discharge conditions, and the cell voltages are not equalized between the cells having different discharge conditions. Therefore, the discharge loss at the time of equalization can be significantly reduced.

According to a third aspect of the present invention, in the control method of the power supply device for a multiple voltage output type vehicle according to the second aspect, the DC-DC converter for replenishing and charging the lower storage block is further provided in each of the cell voltage equalizing circuits. It is characterized in that it is operated after the operation is completed.

That is, according to the present configuration, the DC-DC converter for transmitting power between the blocks, when the equalization by each cell voltage equalizing circuit is substantially completed, is performed between the blocks using the average cell voltage. Since the voltage (eventually, the SOC) is equalized, the variation in practical dischargeable capacity between the battery blocks after power transmission between the blocks can be significantly reduced, and the risk of occurrence of overcharging can be avoided. be able to.

According to a fourth aspect of the present invention, in the control method of the power supply apparatus for a multiple voltage output type vehicle according to any one of the first to third aspects, furthermore, either the load current of the lower power storage block or the average cell voltage is used. The DC if the electrical parameter having a positive correlation is smaller than the electrical parameter having a positive correlation with either the load current of the higher power storage block or the average cell voltage and the difference is larger than a predetermined first threshold value; Driving a DC converter,
Even if the difference becomes smaller than the first threshold, the driving of the DC-DC converter is continued for a predetermined period or until the difference becomes smaller than a second predetermined value smaller than the first threshold. It is characterized by:

According to this control method, if the load current difference, the average cell voltage difference, the SOC difference, and the like between the two blocks are large to some extent, the DC-DC converter is hysteresis-driven. As a result, since the driving can be performed substantially intermittently, the DC-
It is possible to prevent a decrease in efficiency due to the operation of the DC converter for outputting a small current without downsizing the DC-DC converter.

According to a fifth aspect of the present invention, in the control method of the power supply device for a multiple voltage output type vehicle according to any one of the first to third aspects, furthermore, either the load current of the lower power storage block or the average cell voltage is used. The DC if the electrical parameter having a positive correlation is smaller than the electrical parameter having a positive correlation with either the load current of the higher power storage block or the average cell voltage and the difference is larger than a predetermined first threshold value; -It is characterized in that the DC converter is intermittently driven at a predetermined duty ratio.

According to this control method, when the load current difference, the average cell voltage difference and the SOC difference between the two blocks are large to some extent, the block is intermittently driven at a constant timing.
It is possible to prevent a decrease in efficiency due to the operation of the DC converter for outputting a small current without downsizing the DC-DC converter.

According to a sixth aspect of the present invention, in the control method of the power supply device for a multiple voltage output type vehicle according to the fourth or fifth aspect, further, a positive correlation is made with either the load current of the lower storage block or the average cell voltage. An electrical parameter having a smaller value than the electrical parameter having a positive correlation with either the load current of the higher power storage block or the average cell voltage, and a difference between the electrical parameters being larger than the first threshold value than a second threshold value; It is characterized in that the DC-DC converter is driven continuously when it is larger.

According to this configuration, the DC-DC converter is continuously driven when the SOC between the two blocks or the rate of change thereof is considerably large, so that it is possible to prevent the DC-DC converter from increasing in size.

According to a seventh aspect of the present invention, in the control method of the power supply device for a multiple voltage output type vehicle according to any one of the first to sixth aspects, the required power value to be supplied to the battery block for low power source voltage output is further provided. Calculate the device operation efficiency at the time of the partial load continuous operation of the DC-DC converter and the device operation efficiency at the time of the intermittent operation when outputting the average power equal to, and the device operation efficiency at the time of the intermittent operation is If the operation efficiency of the device during continuous operation with partial load exceeds
-It is characterized in that the DC converter is operated intermittently. Here, the continuous operation with partial load means an operation in which the output current is continuously output, and includes an operation by duty control by PWM (pulse width modulation) of the DC-DC converter. The intermittent operation here means an operation in which the output current is periodically interrupted.

With this configuration, the intermittent operation is performed only when the intermittent operation of the DC-DC converter has higher efficiency than the continuous operation at the partial load duty ratio. Can be improved. In addition, since the efficiency is compared not only with the efficiency of the DC-DC converter but also with the charge and discharge efficiency of the battery, the efficiency can be improved.

According to an eighth aspect of the present invention, in the control method of the power supply device for a multiple voltage output type vehicle according to any one of the first to seventh aspects, the DC-DC converter is further provided during an off period of an ignition switch of the vehicle. It is characterized in that the vehicle is driven for a predetermined time every predetermined period.

This makes it possible to improve the efficiency of the DC-DC converter when a low-voltage load is used when the ignition switch is off.

According to a ninth aspect of the present invention, in the control method of the power supply apparatus for a multiple voltage output type vehicle according to any one of the first to eighth aspects, the DC voltage when the vehicle speed is lower than a predetermined value is further reduced.
The output of the DC converter is reduced more than the output of the DC-DC converter when the vehicle speed is equal to or higher than the predetermined value.

In this way, the DC-DC converter at the time of low vehicle speed can be obtained while securing the minimum necessary function.
-Overheating of the DC converter can be suppressed.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the following examples.

[0035]

Embodiment 1 A multiple voltage output type power supply device according to Embodiment 1 is shown in FIG.
This will be described with reference to FIG.

(Circuit configuration) 13 is a lead assembled battery in which three lead batteries (battery blocks referred to in the present invention) 111, 112 and 113 are connected in series, 161 is a low-voltage load, 162 is a high-voltage load, 181, 182 is a DC-DC converter, 17
Is a generator with a built-in rectifier, and 22 is a controller.

Reference numeral 151 denotes a lower terminal of the battery pack 13, 152 denotes an intermediate terminal connected to the connection point 141 between the lead batteries 111 and 112, and 153 denotes a higher terminal of the lead battery. Since the average voltage of the lead battery 13 is approximately 12 V, the voltage of the intermediate terminal 152 is approximately 12 V, and a low-voltage load 161 (eg, ECU, room light, car audio, etc.) is connected. Battery pack 1
The voltage of the positive electrode terminal 153 is about 36.0 V, and a high voltage load 162 (motor for electric power steering, electric compressor for air conditioner, electric water pump, etc.) is connected. An engine-driven rectifier built-in generator 17 is connected between both ends of the battery pack 13.
713 charges the battery pack 13, and loads 161 and 1
62.

The first DC-DC converter 181
Switching element 201 such as OS-FET, transformer 1
91 and a diode 211. A pair of input terminals
Connection point 141 between lead batteries 111 and 112 and lead battery 11
The pair of output terminals are connected to a connection point 142 between the lead batteries 2 and 113, and a pair of output terminals are connected to a connection point 141 between the lead batteries 111 and 112 and a negative electrode terminal 151 of the battery pack 13. The power of the lead battery 113 is transmitted to the lead battery 111 by the switching of the switching element 201.

The second DC-DC converter 182
Switching element 202 such as OS-FET, transformer 1
92 and a diode 212. A pair of input terminals
The connection point 142 between the lead batteries 112 and 113 and the positive terminal 153 of the battery pack 13 are connected. The pair of output terminals is connected to the connection point 141 of the lead batteries 111 and 112 and the negative terminal 151 of the battery pack 13. The power of the lead battery 113 is transmitted to the lead battery 111. The controller 22
Controls the switching elements 201 and 202.

(Operation) In FIG. 1, the power supply to the load 162 is performed by the lead battery 111, the lead battery 112, the lead battery 113 and the generator 17, and the power supply to the load 161 is performed by the first lead battery 111. From the lead battery 112 via the DC-DC converter 181 and from the lead battery 113 via the DC-DC converter 182. Lead battery 1
By controlling the amount of power conversion of the DC-DC converters 181 and 182 so that the voltages of 11 to 113 are substantially equal to each other, the capacities of all the cells of the assembled battery 13 can be equalized.

[0041]

Embodiment 2 Another embodiment will be described with reference to FIG.

Ten lithium batteries (cells) 111 to 1
The assembled battery 13 in which the 110s are connected in series includes a lower power storage block 121 including lithium batteries (cells) 111 to 114 and a higher power storage block 122 including lithium batteries (cells) 115 to 1110.

The average voltage of a lithium battery (cell) is approximately 3.
6V, the negative terminal 151 and the intermediate terminal 1 of the battery pack
52 is approximately 14.4 volts and the low voltage load 16
1 is connected. The voltage of the assembled battery 13 is approximately 36.0 V
And the high voltage load 162 is connected.

The cell equalizing circuit 231 is connected to each terminal of each of the lithium batteries 111 to 114 of the lower storage block 121, and the cell equalizing circuit 232 is connected to each of the terminals of the lithium batteries 115 to 1110 of the higher storage block 122. I have. The cell voltage equalizing circuit 231 eliminates variations in the cell voltage in the lower power storage block 121, and the cell voltage equalizing circuit 232 controls the higher power storage block 122.
Cell voltage variations within the cell.

The cell voltage equalizing circuits 231 and 232 are supplied with operating power from a battery block to be equalized, and are arranged close to the battery block. Further details of the cell voltage equalization circuit will be described later.

The DC-DC converter 18 is a MOS-F
It comprises a switching element 20, such as an ET, a transformer 19, and a diode 21. The pair of input terminals are connected to the positive terminal 153 of the battery pack 13 and the connection point 14 between the lithium batteries 114 and 115, and the pair of output terminals are connected to the connection point 14 between the lithium batteries 114 and 115 and the negative electrode of the battery pack 13. Connected to terminal 151. DC-DC converter 1
8 transmits the power of the higher power storage block 122 to the lower power storage block 121. The controller 22 controls the switching element 20.

FIG. 3 shows an example of the cell voltage equalizing circuits 231 and 232.

The battery block 31 includes N cells 321 to 3
2N are connected in series. 331 to 33N are resistance voltage dividing circuits connected in series to each other and supplied with power from the battery block 31.

The potential of each terminal of the resistance voltage dividing circuit and the positive potential of each of the cells 321 to 32N of the battery block are compared by comparators 341 to 34 (N-1), and the result is input to the logic circuit 35. You. The logic circuit 35 determines a cell whose cell voltage is higher than the average voltage based on the comparison result of each comparator output, and discharge switches 371 to 37 of the individual discharge circuit corresponding to the cell whose cell voltage is higher than the average voltage.
N is turned on, the energy of the cells is consumed by the discharge resistors 361, 362,..., 36N, and the voltages are equalized.

According to the apparatus of this embodiment, the voltage can be controlled within the range of use in units of cells, so that it is suitable when a lithium battery, an electric double layer capacitor or the like is used.

(Modification) A modification will be described below with reference to FIG.

This modification is different from the battery block 12 shown in FIG.
1 is a battery block 122 composed of cells 143 and 144
And a battery block 121 composed of cells 111 and 112, and the power of the battery block 122 is
1 is characterized by the fact that power is transmitted. To enable this power transmission, a DC-DC converter 181 is added. The battery pack 13 divided into three blocks has three output terminals 152 to 154, each of which has the lowest voltage load 1.
61, a low voltage load 162, and a high voltage load 163. 141 and 142 are connection points between the battery blocks, respectively.

(Modification) A modification will be described below with reference to FIG.

This modification is characterized in that the second generator 24 is added to both ends of the lower power storage block 121 in the circuit of FIG.

As a result, a part of the required current of the low-voltage load 161 is borne by the generator 24, so that the burden on the DC-DC converter 18 can be reduced.

[0056]

Embodiment 3 Another embodiment will be described with reference to FIGS.

A characteristic example of the efficiency with respect to the output of the DC-DC converter 18 described above will be described. 250W-600W
The efficiency is almost flat in the output range of
On the other hand, when the power is 250 W or less, the efficiency is significantly reduced. That is, the DC-DC converter 18 has poor partial load efficiency.

However, for example, when the vehicle decelerates,
In some cases, the low-voltage load 161 consumes the regenerated power. At this time, the power consumption of the low-voltage load 161 is reduced by 20 on average.
If it is 0 W, the DC-DC converter 18
It is necessary to output 0 W, and the power loss is greater than when 300 W to 600 W is output. Therefore, in this embodiment, the efficiency is improved by performing the intermittent operation during the partial load operation of the DC-DC converter 18. Also, in this embodiment, the SOC (state of charge) of the battery
The output of the DC-DC converter is controlled based on the above.
A specific example of the control will be described in more detail with reference to FIGS. 7 shows a change in the SOC of the battery block 121, FIG. 8 shows a change in the output of the DC-DC converter 18, and FIG. 9 shows a change in the output of the battery block 121. The controller 22 calculates the SOC of the battery block (lower power storage block) 121. When the SOC decreases to 50%, the controller 22 operates the DC-DC converter 18 at an output of 400W, and outputs 20 of the 400W.
0W is supplied to the low-voltage load, and the remaining 200W is temporarily stored in the battery block 121. Next, when the SOC rises to 60%, the output of the DC-DC converter 18 is stopped, and only the battery block 121 supplies 200 W to the low-voltage load.

However, when the DC-DC converter 18 is operated intermittently as described above, the battery block 121
It is preferable to perform the above-described intermittent drive when the power consumption of the low-voltage load 161 is equal to or less than a predetermined value, and stop the intermittent drive when the power consumption of the low-voltage load 161 is equal to or less than a predetermined value. .

This will be described in detail below. When operating with an output according to the load power consumption in real time, there is no loss due to battery charging and discharging, and the total energy efficiency E1 is: E1 = {0.4 + 0.6ηDC (0.6PL) / 100}
× 100 [%]. Here, PL is the power consumption (W) of the low voltage load,
ηDC (P) is the efficiency of the DC-DC converter 18 and is a function of the output p. An example of ηDC (P) is as shown in FIG. On the other hand, the predetermined output Pconst
In the case of the intermittent operation, the energy is temporarily stored in the battery, so that a loss due to the charging and discharging of the battery occurs, and the total energy efficiency E2 is E2 = [0.4+ {0.6ηDC (Pconst) / 100}.
・ ｛Ηbat1 (Pconst-PL) / 100｝ ・ ｛ηbat2
(PL) / 100 °] × 100 [%]. Where ηbat1 is the charging efficiency (%) of the battery, ηbat2
Is the discharge efficiency (%) of the battery, which is a function of charge power and discharge power, respectively. Although the charging efficiency and the discharging efficiency change depending on the internal resistance of the battery, an example is shown in FIG.
By comparing E1 and E2, if E1 ≧ E2, the operation is performed in real time with an output corresponding to the load power consumption, and if E1 <E2, the operation is intermittent and the most efficient operation is possible. The internal resistance of a single cell is 2 mΩ · Pconst = 400
FIG. 11 shows an example in which E1 and E2 are compared under the condition of W. When the power consumption PL of the low-voltage load is about 300 W or more, E1 ≥ E2, and the operation is performed in real time with an output corresponding to the load power consumption. When the power consumption PL is smaller than about 300 W, E1 <E2, so that the operation is intermittent. What is necessary is just to perform the control which makes a general operation. In the above control example, the SOC of the battery
Was used to control the output of the DC-DC converter 18, but similar control may be performed using the terminal voltage of the battery.

When such control is performed, since the SOC of the battery block has a certain measurement error, the cell voltage is adjusted so that the SOC and the voltage are within the allowable variation range in consideration of the variation. Perform equalization. Thereby, the average efficiency of the DC-DC converter can be maintained high in a wide output range.

[0062]

Embodiment 4 Another embodiment will be described with reference to FIGS.

A large-output type DC-DC converter capable of producing a maximum output of several hundred watts or more from the power supply capability required when the ignition switch is turned on is consumed for memory backup of the ECU when the ignition switch is turned off. If an attempt is made to operate with extremely low power (for example, about 200 mW), there is a problem that the operation becomes unstable and the normal operation is not performed. In the present embodiment, as a method for solving this point, an ignition switch O
At the time of FF, control for intermittent operation is performed at a predetermined cycle.

The specific control will be described with reference to FIGS. FIG. 12 shows the ignition switch O
ON / OFF of the power supply of the controller 22 at the time of FF
The state of is shown. In this way, the controller 22 repeats the periodic operation of turning on the power for several tens of seconds, for example, about once every six hours by a timer or the like. This ON
During the period, the controller measures the voltage of the battery block 121 to which the ECU is connected.
The power of about 400 W is moved from the battery 22 to the battery block 121 for about 15 seconds. On the other hand, when the voltage is higher than the predetermined value, the power is not moved. FIG. 13 shows the voltage change of the battery block 121, and FIG. 14 shows the output of the DC-DC converter 18. Assuming that the time is t, at t = 6 (h), the voltage exceeds the predetermined value (14.4 V), so that D
Although the C-DC converter does not operate, at t = 12 (h), the voltage is equal to or lower than the predetermined value (14.4 V), and the DC-DC converter outputs 400 W for 15 seconds to charge the battery block 121. . By repeating such an operation, power for backing up the ECU memory can be supplied stably.

According to this embodiment, a single DC-DC converter can stably supply the power consumption in both the ON state and the OFF state of the ignition switch of the vehicle. Cost reduction becomes possible.

[0066]

Embodiment 5 Another embodiment will be described with reference to FIGS.

Even when 400 W is output using a DC-DC converter having a maximum power conversion efficiency of 90%, 40 W
Power is turned into heat. Therefore, the DC-DC converter 1
8 is usually cooled by a cooling mechanism such as a fin. Forced convection cooling using the traveling wind is possible when the vehicle is traveling, but when the vehicle is stopped or traveling at a low speed, the traveling wind is not sufficiently obtained, so that it is necessary to perform forced cooling with a fan. However, there is a problem that the power consumption of the fan lowers the efficiency.

Therefore, in this embodiment, when the vehicle speed is lower than the predetermined value and the traveling wind is not sufficiently obtained, the DC-DC converter is controlled as little as possible to control the heat generation.

Specific control will be described with reference to FIGS. FIG. 15 shows changes in vehicle speed, and FIG.
FIG. 17 shows the output of the DC converter 18 and FIG.

When the vehicle speed is higher than the predetermined value and the traveling wind is sufficiently obtained, the DC-DC converter 18 performs the output, but when the vehicle speed is lower than the predetermined value (for example, 10 km / h), the traveling wind is sufficiently obtained. If not, the output of the DC-DC converter 18 is stopped to suppress heat generation. DC-DC
While the output of the converter 18 is stopped, power is temporarily supplied from the battery block 121 to the low-voltage load, and the power is replenished during a period when the vehicle speed exceeds a predetermined value.

When the vehicle speed is equal to or lower than the predetermined value, only the energy stored in the battery block 121 is expected to be consumed. When the vehicle speed is higher than the predetermined value, the voltage or the SOC of the battery block 121 is used. Is controlled to be higher than those of the other battery blocks by a predetermined amount, it is possible to cope with a case where the state where the vehicle speed is equal to or lower than the predetermined value continues for a relatively long time.

The above-described intermittent operation technique of the DC-DC converter will be further supplementarily described.

The conventional DC-DC converter detects electric parameters related to the capacity (SOC) of the battery block, for example, voltage, current, integrated current Ah, SOC, etc., and detects these electric parameters between the battery blocks. The feedback control is performed so that the difference between the two becomes zero. However, if the output current difference between the battery blocks is small, DC-D
As soon as the driving of the C converter is started, the above-mentioned difference is eliminated and the DC-DC converter is stopped, so that the operation becomes inevitably an intermittent operation. At this time, control is also performed to reduce the output current by shortening the on-time of the switching element 20 of the DC-DC converter within a range in which the battery block 121 can be charged, based on the fact that the difference between the electric parameters is small. However, since losses such as switching loss and iron loss of the DC-DC converter occur, the efficiency naturally decreases with a partial load.

Therefore, electric parameters related to the capacity (SOC) of the battery block (lower power storage block) 121, for example, voltage, current, current integrated amount Ah, SOC
Is the other battery block (higher power storage block) 12
(2) delaying the operation of the DC-DC converter until the electric parameter becomes smaller than a certain threshold by more than
Alternatively, even if the difference between the electric parameters between the two battery blocks is eliminated, the operation of the DC-DC converter is continued to some extent to extend the operation time of one DC-DC converter and reduce the output current of the DC-DC converter. Increase.

For example, the operation delay may be determined by judging whether the detected difference between the electric parameters exceeds a predetermined value and starting the operation of the DC-DC converter only when the difference exceeds the predetermined value. In order to maintain the operation of the DC-DC converter to a certain extent even if the difference between the electric parameters is eliminated, the electric parameters related to the capacity (SOC) of the battery block (lower storage block) 121 need not be set at the time when the difference is eliminated. For example, so-called hysteresis (operation start threshold) in which the operation of the DC-DC converter is continued until the voltage, current, current integration amount Ah, and SOC become larger than that of battery block (higher power storage block) 122 by a certain threshold or more. Control operation for setting the operation stop threshold higher than the value may be performed.

Alternatively, when the difference between the electric parameters is small, the forced operation may be performed intermittently for a certain period of time. Thereby, the battery block 121 is overcharged,
Thereafter, this overcharging is eliminated, and a long-term DC-DC converter operation stop occurs until the difference between the electric parameters reaches a value at which the next charging should be started.
This makes it possible to perform the intermittent operation of the DC-DC converter in which one operation period is relatively long or the output during operation is improved, and the average efficiency thereof can be improved.

(Examples of Control of Examples 3 to 5) Examples of control of Examples 3 to 5 will be described below with reference to the flowchart shown in FIG.

First, it is determined whether or not the ignition switch has been turned on (S100). If the ignition switch has been turned on, it is determined whether or not the vehicle speed is equal to or higher than a predetermined value (S102). If the vehicle speed is equal to or higher than a predetermined value, the efficiencies E1, E of the DC-DC converter
2 is calculated (S104).

Here, the efficiency E1 means the efficiency of the DC-DC converter 18 when the DC-DC converter 18 shown in FIG. 2 is operated with an output corresponding to the power consumption of the low-voltage load 161. E2 is the DC-D shown in FIG.
This means the efficiency of the DC-DC converter 18 when the C converter 18 is operated intermittently at an output at which the average efficiency is the best.

Next, it is checked whether the efficiency E1 is equal to or higher than the efficiency E2 (S110). If YES, the DC-DC converter 18 is operated with an output corresponding to the power consumption of the low-voltage load 161 (S110). If there is, the DC-DC converter 18 is operated intermittently with the output at which the average efficiency is the best (S
112).

If the vehicle speed is lower than the predetermined value in step S102, it is checked whether the voltage of the lower power storage block 121 is higher than the predetermined value. If YES, the operation of the DC-DC converter 18 is stopped. Step S104
Proceed to.

In step S118, it is checked whether or not the timer built in the controller 22 has notified the expiration of the predetermined count (S118). If there is no notification, the step not shown is executed, and the process returns to S100. This timer is a circulation timer that outputs a signal for the above-mentioned notification every time a predetermined time elapses during the off period of the ignition switch.

If the notification is made in S118, it is checked whether or not the voltage of the lower power storage block 121 is equal to or lower than a predetermined value.
In the case of ES, the DC-DC converter 18 is operated for a predetermined time to transmit power from the higher power storage block 122 to the lower power storage block 121 (S122), and thereafter, the controller 22 other than the timer and the circuit associated therewith is used.
Power supply to the circuit part of
2 is put to sleep (S124). Step S1
If NO in step 20, the flow jumps to step S124 to put the controller 22 in a sleep state.

According to this configuration, the intermittent operation is performed only when the intermittent operation of the DC-DC converter is higher in efficiency than the continuous operation at the partial load duty ratio. Can be improved.

If the vehicle speed is lower than the predetermined value, the cooling effect of the DC-DC converter 18 due to the traveling wind is reduced. In this case, the minimum allowable SOC (terminal voltage) for the lower power storage block 121 is secured. Under such conditions, the operation of the DC-DC converter 18 is stopped as much as possible to suppress the heat generation of the DC-DC converter 18, thereby improving the durability of the DC-DC converter 18.

Further, as the vehicle electric load when the ignition is turned off, there is a reduction in the capacity of the lower power storage block 121 due to the use of the low-voltage load 161. At this time, the power consumption of the low-voltage load 161 is reduced by the full load of the DC-DC converter 18. Very small compared to the transmitted power during operation, DC-
The DC converter 18 is in a small partial load operation state, and the efficiency is greatly reduced. Therefore, in this control example, when the ignition is turned off (the battery is not charged), the power transmission of the DC-DC converter enough to keep the capacity of the lower power storage block 121 at an allowable predetermined value is intermittently performed (every predetermined time). ), It is possible to avoid a decrease in efficiency due to the partial load operation of the DC-DC converter 18.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a multiple voltage output type vehicle power supply device according to a first embodiment.

FIG. 2 is a circuit diagram showing a multiple voltage output type vehicle power supply device according to a second embodiment.

FIG. 3 is a circuit diagram showing an example of a cell voltage equalization circuit.

FIG. 4 is a circuit diagram showing a modification of the second embodiment.

FIG. 5 is a circuit diagram showing a modification of the second embodiment.

FIG. 6 is a characteristic diagram illustrating a control method of the multiple voltage output type vehicle power supply device according to the third embodiment.

FIG. 7 is a timing chart illustrating a control method of the power supply device for a multiple voltage output type vehicle according to the third embodiment.

FIG. 8 is a timing chart showing a control method of the multiple voltage output type vehicle power supply device according to the third embodiment.

FIG. 9 is a timing chart showing a control method of the multiple voltage output type vehicle power supply device according to the third embodiment.

FIG. 10 is a characteristic diagram illustrating a control method of the power supply device for a multiple voltage output type vehicle according to the third embodiment.

FIG. 11 is a characteristic diagram illustrating a control method of the power supply device for a multiple voltage output type vehicle according to the third embodiment.

FIG. 12 is a timing chart illustrating a control method of the power supply device for a multiple voltage output type vehicle according to the fourth embodiment.

FIG. 13 is a timing chart illustrating a control method of the multiple voltage output type vehicle power supply device according to the fourth embodiment.

FIG. 14 is a timing chart showing a control method of the multiple voltage output type vehicle power supply device according to the fourth embodiment.

FIG. 15 is a timing chart illustrating a control method of the multiple voltage output type vehicle power supply device according to the fifth embodiment.

FIG. 16 is a timing chart showing a control method of the multiple voltage output type vehicle power supply device of the fifth embodiment.

FIG. 17 is a timing chart showing a control method of the multiple voltage output type vehicle power supply device according to the fifth embodiment.

FIG. 18 is a flowchart illustrating a control example of Examples 3 to 5.

[Explanation of symbols]

 13 assembled battery (multiple voltage output type power storage unit) 111 battery block (lower power storage block) 112 battery block (higher power storage block) 113 battery block (higher power storage block) 181 DC-DC converter 182 DC-DC converter

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideharu Yoshida 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (reference) 5G003 AA07 BA03 CA12 GA01 GB03 5H030 AA03 AA04 AA06 AS08 BB01 BB10 FF42 FF43 FF51

Claims (9)

[Claims] 1. A lower power storage block for outputting a low power supply voltage to a low voltage load, and a high power supply voltage is output to a high voltage load together with the lower power storage block connected in series to a higher side of the lower power storage block. A plurality of higher power storage blocks connected in series to one another, and a power generation unit for transmitting power to a series-connected power storage block group including the lower power storage block and the higher power storage blocks connected in series to each other, mounted on the vehicle. In the multiple voltage output type vehicle power supply device, the voltage between both ends of the higher power storage block is converted into a voltage and applied to both ends of the lower power storage block, so that only the lower power storage block is stored by the power stored in the higher power storage block. And a DC-DC converter for supplementary charging of the lower storage block An inter-block power transmission control unit that detects and compares an electric parameter related to an average cell voltage of each of the battery blocks, and that approximately matches the average cell voltage of each of the battery blocks based on the comparison result. Characteristic multi-voltage output type vehicle power supply device. 2. The power supply device for a multiple voltage output type vehicle according to claim 1, further comprising: a plurality of cell voltage equalization circuits individually connected to each of said battery blocks each having a plurality of cells connected in series; The multiple voltage output type vehicle power supply device, wherein each of the cell voltage equalizing circuits equalizes the voltage of each of the cells in the battery block to which the cell is connected. 3. The control method for a power supply device for a multiple voltage output type vehicle according to claim 2, wherein the DC-DC converter for supplementary charging of the lower storage block is operated in a state where the operation of each of the cell voltage equalizing circuits is completed. A method for controlling a power supply device for a multiple voltage output type vehicle, comprising: 4. The control method for a multiple voltage output type vehicle power supply device according to claim 1, wherein the electric parameter having a positive correlation with either the SOC of the lower power storage block or the average cell voltage. Driving the DC-DC converter when the electrical parameter having a positive correlation with either the load current of the higher power storage block or the average cell voltage and the difference is greater than a predetermined first threshold, Even if the difference is smaller than the first threshold, the driving of the DC-DC converter is continued for a predetermined period or until the difference is smaller than a second predetermined value smaller than the first threshold. A method for controlling a power supply device for a multiple voltage output type vehicle, comprising: 5. The control method for a multiple voltage output type vehicle power supply device according to claim 1, wherein the electric parameter having a positive correlation with either the SOC of the lower power storage block or the average cell voltage. When the electric parameter having a positive correlation with either the load current of the higher storage block or the average cell voltage is smaller than the electric parameter and the difference is larger than a predetermined first threshold value, the DC-DC converter is switched to a predetermined duty ratio. A method of controlling a power supply device for a multiple voltage output type vehicle, wherein the power supply device is intermittently driven. 6. The control method for a power supply device for a multiple voltage output type vehicle according to claim 4, wherein the electric parameter having a positive correlation with either the SOC of the lower power storage block or the average cell voltage is used as the higher power storage power. The DC-DC if the electrical parameter having a positive correlation to either the load current of the block or the average cell voltage and less than a second threshold greater than the first threshold; A method for controlling a multiple voltage output type vehicle power supply device, characterized by continuously driving a converter. 7. The control method for a power supply device for a multiple voltage output type vehicle according to claim 1, wherein an average power equal to a required power value to be supplied to the battery block for low power supply voltage output is output. Calculating the device operation efficiency during the partial load continuous operation of the DC-DC converter and the device operation efficiency during the intermittent operation, wherein the device operation efficiency during the intermittent operation is the same as during the partial load continuous operation. A method of controlling a power supply device for a multiple voltage output type vehicle, wherein the DC-DC converter is operated intermittently when the operation efficiency of the vehicle is exceeded. 8. A control method for a power supply device for a multiple voltage output type vehicle according to claim 1, wherein said DC-DC converter is turned on for a predetermined time every predetermined period during an off period of an ignition switch of said vehicle. A method for controlling a power supply device for a multiple voltage output type vehicle, comprising: 9. A control method for a power supply apparatus for a multiple voltage output type vehicle according to claim 1, wherein an output of said DC-DC converter when a vehicle speed is less than a predetermined value, said vehicle speed is adjusted to said predetermined speed. D when the value is not less than
A control method for a multiple voltage output type vehicle power supply device, characterized in that the output is reduced from the output of a C-DC converter.